Re: [PATCH v5] x86: Avoid pr_cont() in show_opcodes().
* Tetsuo Handa wrote: > On 2018/07/18 20:57, Ingo Molnar wrote: > > > > * Tetsuo Handa wrote: > > > >> Since syzbot is confused by concurrent printk() messages [1], > >> this patch changes show_opcodes() to use %ph format string. > >> > >> When we start adding prefix to each line of printk() output, > >> we will be able to handle concurrent printk() messages. > >> > >> [1] https://syzkaller.appspot.com/text?tag=CrashReport=139d342c40 > >> > >> Signed-off-by: Tetsuo Handa > >> Signed-off-by: Rasmus Villemoes > > > > Wasn't that variant of the patch written by Rasmus? > > Rasmus Villemoes taught me that we can use "%*ph" format string and pass > length as arguments for "*" part. Then, since Joe Perches suggested me to > use #define for length variable, I updated to use "#define length immediate" > and replaced "%*ph" with "%" __strigify(length) "ph" and removed length from > arguments. That is v5 patch. > > > > > If so then the changelog should start with: > > > > From: Rasmus Villemoes > > OK. I posted v6 patch with From: line updated. Please do that only if it was mainly written by him - otherwise just tell me that it's yours and I'll apply it as such. Thanks, Ingo
Re: [PATCH v5] x86: Avoid pr_cont() in show_opcodes().
* Tetsuo Handa wrote: > On 2018/07/18 20:57, Ingo Molnar wrote: > > > > * Tetsuo Handa wrote: > > > >> Since syzbot is confused by concurrent printk() messages [1], > >> this patch changes show_opcodes() to use %ph format string. > >> > >> When we start adding prefix to each line of printk() output, > >> we will be able to handle concurrent printk() messages. > >> > >> [1] https://syzkaller.appspot.com/text?tag=CrashReport=139d342c40 > >> > >> Signed-off-by: Tetsuo Handa > >> Signed-off-by: Rasmus Villemoes > > > > Wasn't that variant of the patch written by Rasmus? > > Rasmus Villemoes taught me that we can use "%*ph" format string and pass > length as arguments for "*" part. Then, since Joe Perches suggested me to > use #define for length variable, I updated to use "#define length immediate" > and replaced "%*ph" with "%" __strigify(length) "ph" and removed length from > arguments. That is v5 patch. > > > > > If so then the changelog should start with: > > > > From: Rasmus Villemoes > > OK. I posted v6 patch with From: line updated. Please do that only if it was mainly written by him - otherwise just tell me that it's yours and I'll apply it as such. Thanks, Ingo
Re: [PATCH v5] x86: Avoid pr_cont() in show_opcodes().
On 2018/07/18 20:57, Ingo Molnar wrote: > > * Tetsuo Handa wrote: > >> Since syzbot is confused by concurrent printk() messages [1], >> this patch changes show_opcodes() to use %ph format string. >> >> When we start adding prefix to each line of printk() output, >> we will be able to handle concurrent printk() messages. >> >> [1] https://syzkaller.appspot.com/text?tag=CrashReport=139d342c40 >> >> Signed-off-by: Tetsuo Handa >> Signed-off-by: Rasmus Villemoes > > Wasn't that variant of the patch written by Rasmus? Rasmus Villemoes taught me that we can use "%*ph" format string and pass length as arguments for "*" part. Then, since Joe Perches suggested me to use #define for length variable, I updated to use "#define length immediate" and replaced "%*ph" with "%" __strigify(length) "ph" and removed length from arguments. That is v5 patch. > > If so then the changelog should start with: > > From: Rasmus Villemoes OK. I posted v6 patch with From: line updated. > > Thanks, > > Ingo >
Re: [PATCH v5] x86: Avoid pr_cont() in show_opcodes().
On 2018/07/18 20:57, Ingo Molnar wrote: > > * Tetsuo Handa wrote: > >> Since syzbot is confused by concurrent printk() messages [1], >> this patch changes show_opcodes() to use %ph format string. >> >> When we start adding prefix to each line of printk() output, >> we will be able to handle concurrent printk() messages. >> >> [1] https://syzkaller.appspot.com/text?tag=CrashReport=139d342c40 >> >> Signed-off-by: Tetsuo Handa >> Signed-off-by: Rasmus Villemoes > > Wasn't that variant of the patch written by Rasmus? Rasmus Villemoes taught me that we can use "%*ph" format string and pass length as arguments for "*" part. Then, since Joe Perches suggested me to use #define for length variable, I updated to use "#define length immediate" and replaced "%*ph" with "%" __strigify(length) "ph" and removed length from arguments. That is v5 patch. > > If so then the changelog should start with: > > From: Rasmus Villemoes OK. I posted v6 patch with From: line updated. > > Thanks, > > Ingo >
Re: [PATCH v5] x86: Avoid pr_cont() in show_opcodes().
* Tetsuo Handa wrote: > Since syzbot is confused by concurrent printk() messages [1], > this patch changes show_opcodes() to use %ph format string. > > When we start adding prefix to each line of printk() output, > we will be able to handle concurrent printk() messages. > > [1] https://syzkaller.appspot.com/text?tag=CrashReport=139d342c40 > > Signed-off-by: Tetsuo Handa > Signed-off-by: Rasmus Villemoes Wasn't that variant of the patch written by Rasmus? If so then the changelog should start with: From: Rasmus Villemoes Thanks, Ingo
Re: [PATCH v5] x86: Avoid pr_cont() in show_opcodes().
* Tetsuo Handa wrote: > Since syzbot is confused by concurrent printk() messages [1], > this patch changes show_opcodes() to use %ph format string. > > When we start adding prefix to each line of printk() output, > we will be able to handle concurrent printk() messages. > > [1] https://syzkaller.appspot.com/text?tag=CrashReport=139d342c40 > > Signed-off-by: Tetsuo Handa > Signed-off-by: Rasmus Villemoes Wasn't that variant of the patch written by Rasmus? If so then the changelog should start with: From: Rasmus Villemoes Thanks, Ingo
[PATCH v5] x86: Avoid pr_cont() in show_opcodes().
Since syzbot is confused by concurrent printk() messages [1],
this patch changes show_opcodes() to use %ph format string.
When we start adding prefix to each line of printk() output,
we will be able to handle concurrent printk() messages.
[1] https://syzkaller.appspot.com/text?tag=CrashReport=139d342c40
Signed-off-by: Tetsuo Handa
Signed-off-by: Rasmus Villemoes
Cc: Borislav Petkov
Cc: Thomas Gleixner
Cc: Peter Zijlstra
Cc: Josh Poimboeuf
Cc: Linus Torvalds
Cc: Andy Lutomirski
---
arch/x86/kernel/dumpstack.c | 29 +
1 file changed, 9 insertions(+), 20 deletions(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 666a284..0821da3 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -22,8 +22,6 @@
#include
#include
-#define OPCODE_BUFSIZE 64
-
int panic_on_unrecovered_nmi;
int panic_on_io_nmi;
static int die_counter;
@@ -93,26 +91,17 @@ static void printk_stack_address(unsigned long address, int
reliable,
*/
void show_opcodes(u8 *rip, const char *loglvl)
{
- unsigned int code_prologue = OPCODE_BUFSIZE * 2 / 3;
+#define PROLOGUE_SIZE 42
+#define EPILOGUE_SIZE 21
+#define OPCODE_BUFSIZE (PROLOGUE_SIZE + 1 + EPILOGUE_SIZE)
u8 opcodes[OPCODE_BUFSIZE];
- u8 *ip;
- int i;
-
- printk("%sCode: ", loglvl);
- ip = (u8 *)rip - code_prologue;
- if (probe_kernel_read(opcodes, ip, OPCODE_BUFSIZE)) {
- pr_cont("Bad RIP value.\n");
- return;
- }
-
- for (i = 0; i < OPCODE_BUFSIZE; i++, ip++) {
- if (ip == rip)
- pr_cont("<%02x> ", opcodes[i]);
- else
- pr_cont("%02x ", opcodes[i]);
- }
- pr_cont("\n");
+ if (probe_kernel_read(opcodes, rip - PROLOGUE_SIZE, OPCODE_BUFSIZE))
+ printk("%sCode: Bad RIP value.\n", loglvl);
+ else
+ printk("%sCode: %" __stringify(PROLOGUE_SIZE) "ph <%02x> %"
+ __stringify(EPILOGUE_SIZE) "ph\n", loglvl, opcodes,
+ opcodes[PROLOGUE_SIZE], opcodes + PROLOGUE_SIZE + 1);
}
void show_ip(struct pt_regs *regs, const char *loglvl)
--
1.8.3.1
[PATCH v5] x86: Avoid pr_cont() in show_opcodes().
Since syzbot is confused by concurrent printk() messages [1],
this patch changes show_opcodes() to use %ph format string.
When we start adding prefix to each line of printk() output,
we will be able to handle concurrent printk() messages.
[1] https://syzkaller.appspot.com/text?tag=CrashReport=139d342c40
Signed-off-by: Tetsuo Handa
Signed-off-by: Rasmus Villemoes
Cc: Borislav Petkov
Cc: Thomas Gleixner
Cc: Peter Zijlstra
Cc: Josh Poimboeuf
Cc: Linus Torvalds
Cc: Andy Lutomirski
---
arch/x86/kernel/dumpstack.c | 29 +
1 file changed, 9 insertions(+), 20 deletions(-)
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 666a284..0821da3 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -22,8 +22,6 @@
#include
#include
-#define OPCODE_BUFSIZE 64
-
int panic_on_unrecovered_nmi;
int panic_on_io_nmi;
static int die_counter;
@@ -93,26 +91,17 @@ static void printk_stack_address(unsigned long address, int
reliable,
*/
void show_opcodes(u8 *rip, const char *loglvl)
{
- unsigned int code_prologue = OPCODE_BUFSIZE * 2 / 3;
+#define PROLOGUE_SIZE 42
+#define EPILOGUE_SIZE 21
+#define OPCODE_BUFSIZE (PROLOGUE_SIZE + 1 + EPILOGUE_SIZE)
u8 opcodes[OPCODE_BUFSIZE];
- u8 *ip;
- int i;
-
- printk("%sCode: ", loglvl);
- ip = (u8 *)rip - code_prologue;
- if (probe_kernel_read(opcodes, ip, OPCODE_BUFSIZE)) {
- pr_cont("Bad RIP value.\n");
- return;
- }
-
- for (i = 0; i < OPCODE_BUFSIZE; i++, ip++) {
- if (ip == rip)
- pr_cont("<%02x> ", opcodes[i]);
- else
- pr_cont("%02x ", opcodes[i]);
- }
- pr_cont("\n");
+ if (probe_kernel_read(opcodes, rip - PROLOGUE_SIZE, OPCODE_BUFSIZE))
+ printk("%sCode: Bad RIP value.\n", loglvl);
+ else
+ printk("%sCode: %" __stringify(PROLOGUE_SIZE) "ph <%02x> %"
+ __stringify(EPILOGUE_SIZE) "ph\n", loglvl, opcodes,
+ opcodes[PROLOGUE_SIZE], opcodes + PROLOGUE_SIZE + 1);
}
void show_ip(struct pt_regs *regs, const char *loglvl)
--
1.8.3.1
